Innovazione e semplificazione nella riabilitazione protesica ed implantare
:Epifania E.1,Montesarchio C.
1
Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Naples, Italy
Corresponding author: Prof Epifania Ettore
Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples Federico II
Via Pansini, n.5 80100 Naples, Italy e-mail: [email protected]
ABSTRACT
Often, in cases of completely edentulous patients, there’s a need to replace not only the teeth, but also the support tissues, that subsequently the loss of teeth, are subject to remodeling and resorption. (1) In these cases, a therapeutic choice which gives us the opportunity to replace both the teeth and the support tissues is represented by the “Toronto bridge”. This kind of implant-supported prosthesis is characterized by prosthetic replacement also of the soft and gingival tissues and the possibility to restoring vertical and sagittal skeletal discrepancies.
The objective of this report is to present the case of a completely edentulous patient with atrophy of both arches, treated by positioning 6 implants at the upper arch and 6 implants at the inferior one, that support a Toronto prosthesis, realized with the use of new CAD-CAM technology; also analyzing the aesthetic, functional and patient satisfaction.
INTRODUCTION
Since the 1960s, with the introduction of the osteointegration concept by Branemark(2), recognized by the scientific community as a valid and reproducible process, dental implants are widely used for the rehabilitation of partially and completely edentulous patients, representing a valid alternative to the removable dental prosthesis. Implant therapy(3,4) has rapidly evolved in recent years. We can distinguish two important philosophies: screwed and cemented. Different studies have shown disadvantages and advantages for both types.(5-7)
Toronto bridge prosthesis(8,9) are indicated to overcome the issues of both types of restoration, cemented and screwed, benefiting from their advantages. This type of prosthesis is a screwed-in mesostructure on a variable number of implants. The element of discrimination against a fixed Prosthetics (Implant-Supported) is represented by prosthetic replacement of soft tissue, which are essential in order to obtain optimal esthetic results in case of marked atrophy; reduction of vertical dimension and miss-match between the implant and prosthetic emergencies. The position of the implants does not necessarily have to correspond to the emergence of the teeth, but we must try to make the most of the available bone.
We report the results of the prosthetic restoration in a totally edentulous patient using the new CAD-CAM technology in a “Toronto Bridge” protocol.
A 63-year-old woman comes to us looking for a fixed prosthetic rehabilitation. The patient is subjected to: physiological anamnesis, which shows the absence of allergies, the absence of risk factors: pathological(Diabetes, metabolic syndrome, HIV, neutropenia); environmental (medications, smoking, alcohol and stress); behavioral (Lifestyle and oral hygiene); past pathology anamnesis, the patient does not report: cardiovascular diseases, diabetes, coagulation disorder, hypertension; next pathology anamnesis: the patient complains that she cannot adapt to the use of the removable dental prosthesis, for this reason the patient asks if there is the possibility of making a total fixed prosthesis. The evaluation of satisfaction perceived by patient was assessed by completing a questionnaire(10). The extraoral examination shows the counterclockwise rotation of the jaw resulting from the absence of dental elements, from vertical bone resorption, from bone resorption in a centripetal direction for the maxilla and centrifuge for the mandible. (figure 1) In the intraoral examination there is the absence of lesions of the mucous membranes, the patient is totally edentulous following the extraction of all the teeth carried out about 9 months earlier resulting from chronic periodontitis.
The patient, to our observation, has a complete removable dental prosthesis upper and lower and she requires treatment to replace the removable prosthesis with a fixed implant prosthesis.
Firstly, the TC dentalscan has allowed to highlight, both in the maxilla and mandibular, the presence of a enough quantity of bone in order to make possible the placement of 6 implants to the upper arch and 6 to the inferior arch. In cases of large prosthetic rehabilitations, a surgical guide is often used. The surgical guide helps us during the surgery, because it has holes at the points where the implants will be inserted. In this case, the removable prosthesis of the patient was duplicated for the construction of the surgical guide, since it was considered suitable. The
implant is positioned on the receiving site with a maximum torque of 35 N / cm. The implants used are conical implants Adin Touareg S AB / AE. (11-14)
Once the implants have been placed, we have to wait for the osseointegration 3 months and during that period the patient makes use of her old denture as a temporary prosthesis. After 3 months, we proceed to the exposure of these and we verify the complete osseointegration of all the implants through: clinical examination (absence of pain, absence of mobility, absence of history of infection); radiographic examination (figure 2) (absence of radiographic bone loss <2mm).
We proceed with the positioning of theTrans Mucosal Abutments System TMA (figures 3), which have transgingival heights ranging from 1 to 5mm and angles of 0 °, 17 ° and 30 °. The use of TMA is recommended in cases where the inadequate thickness and bone height prevent implant placement in a prosthetically correct position or when multiple implants are placed it is difficult to position them with similar gingival depth. Therefore, different depths and non-parallel angles can be modified by TMA. Thus, they allow to compensate for the divergence of the positioned implants and to create a unique insertion plan.
After this, the impression is taken by means of a custom-made tray with perforations, according to the technique of the impression with open tray or “pick-up”. Before taking the impression, TMA transfers are screwed to the abutments and rigidly blocked together to avoid possible movement in the impression during the screwing phase of the laboratory analogue. The technique used to block the transfers involves the use of calcinable resin applied between the transfers on a silk floss passed between them. The impression was made through the use of polyvinylsiloxane according to the single step double mix technique impression. Subsequently, to define a correct intermaxillary relationship, occlusal registration plates were made. These
consist of a resin base and a wax rim of rigid consistency and with the same resin a plate was made to make it adhere to the occlusal fork and facilitate the registration of the facial arch. While through the registration plates the vertical dimension was recorded, which is determined exclusively by the dentist. Moreover, the Occlusal Plane has been identified. Once the recordings are finished, the rims are locked between them. The teeth used are Acry Smart artificial teeth in PMMA resin. Acry Smart has the occlusal surfaces of the rear teeth designed following the new concept of wide tripodization and superior grinding efficiency is maintained over time. The teeth assembly takes place by means of “substitution". Assembly is finalized, observing that there is a right relationship between aesthetics and function. The group function is opted for the occlusal scheme.
In order that the bar, obtained from 6AL-4V titanium disks (Grade 5), can be made, a scan of the models, of the gingival portion and of the upper and lower prosthetic project was performed. (figure 4) In addition, to transfer the position and orientation of the implants from the model to the software exocad, we use the scanmarkers. The design of the bar, made using exocad (Figure 5), must take into account the position and orientation of the implants and, in particular, of the prosthetic project. Since, starting from the prosthetic project itself, the thicknesses necessary for the construction of the bar are obtained, in such a way as to obtain a prosthesis that respects all the previously performed recordings. Finally, the bar has been milled by using the CAM software hyperDENT. After, it was prepared for the final stages of processing, namely: staining of the bar with special opaque (figure 6); choice and positioning of mobile prosthesis teeth, following the previous prosthetic project; finally, the Toronto Bridge was finished and polished (figure 7).
The complete work was screwed to the abutments by applying a maximum torque of 15N/cm and at delivery the actual presence of the necessary space between the gingiva and the prosthesis was verified. On delivery, the patient expressed to be very satisfied with the aesthetic result, as going to restore also the gingival component, the lip support was recreated. (Figure 8)
DISCUSSION
The purpose of this case report is to show how the Toronto bridge prosthesis turns out to be a valid prosthetic solution in cases where implants can be inserted, but at the same time there is a marked atrophy of the soft tissues. The real innovation turns out to be the application of the new CAD-CAM methods for the construction of the bar. Which associated with careful study of the case and the precision of the steps, especially as regards the dental impression, gave us the possibility to create a highly precise bar, which allowed us to avoid its eventual separation and subsequent welding. Therefore, we have reduced the passages and obtained a highly precise structure, satisfactory from the aesthetic point of view, and functional with a much lower economic cost.
SUMMARY
The patient's clinical picture, which is accompanied by bone resorption and the need to fill not only the lost teeth, but also of the support tissue, pointed us to a Toronto bridge prosthesis.
REFERENCES
1. Ulm C., Solar T., Blahout R. et all: Reduction of the compact and cancellous bone substance of the edentulous mandible caused by resorpition Oral Surg Oral Med Oral pathol 1992;74:131-136
2. Branemark PI, Hansson BO, Adell R: Osseointegrated implants in the treatment of the edentulous jaw. Experience from a 10-year period. Scand J Plast Reconstr Surg Suppl. 1977;16:1-132.
3. Albrektsson T, Zarb GA. Current interpretation of the osseointegrated response: clinical significance. Int J Prosthodont 1993;6:95-105.
4. Astrand P, Ahlqvist J, Gunne J, Nilson H. Implant treatment of patients with edentulous jaws: a 20-year follow-up. Clin Implant Dent Relat Res. 2008;10(4):207-17.
5. Michalakis KX, Hirayama H, Garefis PD. Cement-retained versus screw-retained implant restorations: a critical review. Int J Oral Maxillofac Implants. 2003;18:719–28.
6. Lee A, Okayasu K, Wang HL. Screw- versus cement-retained implant restorations: current concepts. Implant Dent. 2010;19:8–15.
7. Chee W, Jivraj S. Screw versus cemented implant supported restorations. Br Dent J. 2006;201:501–7.
8. Cicciù M, Risitano G, Maiorana C, Franceschini G. Parametric analysis of the strength in the ''Toronto'' osseous-prosthesis system. Minerva Stomatol. 2009;58(1-2):9–23.
9. Kwon T, Bain PA, Levin L. Systematic review of short- (5-10 years) and long-term (10 years or more) survival and success of full-arch fixed dental hybrid prostheses and supporting implants. J Dent. 2014 Oct;42(10):1228-41.
10. Epifania E, Sanzullo R, Sorrentino R, Ausiello P Evaluation of Satisfaction Perceived by Prosthetic Patients Compared to Clinical and Technical Variables. J Int Soc Prev Community Dent. 2018 May-Jun;8(3):252-258
11. Eitan Mijiritsky, Adi Lorean, Horia Barbu, Ziv Mazor Full-Mouth Implant-supported Rehabilitation with a Flapless Surgical Technique: A Treatment Approach using Computer-Assisted Oral Implant Surgery 10.5005/JP-Journals-10012-1055
12. i r . reit s- nior, DDS, PhDa/Estevam A. Bonfante, DDS, PhDb/Leandro M. Martins, DDS, MScc/ Nelson R.F.A. Silva, DDS, PhDd/Leonard Marotta, DDS, PhDe/Paulo G. Coelho, DDS, PhDf Effect of Implant Diameter on Reliability and Failure Modes of Molar Crowns
13. Mijiritsky E1, Mazor Z, Lorean A, Levin L. Implant diameter and length influence on survival: interim results during the first 2 years of function of implants by a single manufacturer. Implant Dent. 2013 Aug;22(4):394-8.
14. M.M. Goswami, Lt Col,a,∗ Mukul Kumar, Col,b Abhinav Vats, Lt Col,c and A.S. Bansal, Brig, Retdd Evaluation of dental implant insertion torque using a manual ratchet Med J Armed Forces India. 2015 Dec; 71(Suppl 2): S327–S332
FIGURES
Fig. 1 The extraoral examination shows the counterclockwise rotation of the jaw resulting from the absence of dental elements.
Fig. 2 Radiographic evaluation after three months and after the placement of the TMA abutments.
Fig. 3 Lower arch with TMA type abutments positioned.
Fig. 5 Design of the structure using Exocad software.
Fig. 7 Toronto bridge completed.
